The Infant Mystics Society had its origin with a group that began parading in the second year of Mobile's Mardi Gras. 

Mobile's mystic parades first appeared on New Year's Eve in the early 1830's but in 1868 the first group to give the public a similar presentation on Mardi Gras, or "Fat Tuesday," was the Order of Myths. 

The following year saw the organization of the "H.S.S.," or "Hoc Signo Sustineat."  Members of the H.S.S. Society paraded from 1869 until 1872. But, while keeping the "Hoc Signo Sustineat" motto, they  reorganized in 1873 under the name "Infant Mystics." 
 Because the members of the Infant Mystics organization were mainly carried over from the previous "H.S.S.,"  late nineteenth century newspapers in New Orleans consistently referred to the origin of the Infant Mystics as either 1869 instead of 1873, such as those below. 

Times Picayune, February 14, 1876

The Infant Mystics represented for their twenty-weventh anniversary "The Stories We Have Read," in seven floats and the society emblem float, a monster cat. 
                                   New Orleans Times, 1896

Original Officers Included :

F. P. Davis elected as permanent chairperson

Albert E. Mudge served as Prime Minister

First Infant Mystics officers included:
F.P. Davis
T.A. Wilkinson
Dr. Rhett Goode
Charles Spies

There were changes that came when the name "Infant Mystics" was adopted in 1873, including a new constitution, bylaws and new emblems. 
After Four Years of Parading, the H.S.S. disbanded
and Re-organized as the
"Infant Mystics"
on March 25, 1873

Gentlemen of the New Organization,
We the committee appointed at your very flattering meeting last Thursday evening, to submit to your honorable body, a plan of organization, name, constitution, bylaws, etc….

Infant Mystics Constitution 
We the undersigned young men of Mobile being desirous of forming ourselves int oan association to succeed the “H.S.S.” deceased, in the celebration of Mardi Gras by a street carnival and ball for the promotion of our own sociability and pleasure and also for the advancement of the interest of Mobile, and to render her more attractive to the outside world and the rest of mankind...
  From the Times Picayune, March 6, 1878

The Infant Mystics made their first parade as the "H.S.S., " and as it was, somehow or other, supposed that they were only "a crowd of boys, " very little interest, comparatively speaking, was taken in them. Their advent into the circle of mystics was, however, so brilliant, and each of their subsequent representations were so elegant in every respect that public attention turned toward them, despite the suggestion of juvenality, and now it may be safely asserted that they occupy no secondary position among those "who walk behind the clouds." They have so far attempted nothing that they have not done well-- and last night's theme, while within thself a fruitful one, was handled in such a manner as indicated beyond peradventure, that the Infant Mystics are fully matured in the act of interpreting the grandest masters in their delineation of human nature through allegory, history, and romance. 

No Parade in 1888

The Infant Mystics did not parade but gave a grand ball in the Princess Theater, the interior of which was completely transformed as to represent a scene from a picture in Watean. The quests were costumed to suit the Age of Louis Quinze. 

Philadelphia Inquirer,  February 15, 1888

Infant Mystics create the first "scenic ball" in Mobile

 St. Louis Republic, March 6, 1889

IInfant Mystics Briefly disbanded in 1897

Times Picayune, March 3, 1897 

Comic Cowboys Burlesque of Infant Mystic's Breakup

  Times Picayune, March 3, 1897 

 Palmer Pillans, Mobile In Two Centuries